Urea amidolyase is an ATP dependent, HCO3 minus, requiring, biotin containing, urea cleaving enzyme system found in certain fungi and algae. The proposed research would be represented by the following points: 1. Purification of the chlamyodmonas reinhardii urea amidolyase enzymes to homogeneity. 2. Characterization of the Candida utilis and the Chlamydomonas reinhardii urea amidolyase enzymes as to molecular weight, amino acid analysis, biotin content, and antigenic relatedness. 3. Isolation and characterization of subunits of these enzymes.